Mother and Daughter

Image Critiques Nightscape & Astro Critiques
1

CassiopeiaAndromedaNPN.jpg
CassiopeiaAndromedaNPN.jpg1500×1000 1.04 MB

Critique Style Requested: Standard

The photographer is looking for generalized feedback about the aesthetic and technical qualities of their image.

Description

Mother and Daughter depicts both Cassiopeia and Andromeda in the Northern sky. Cassiopeia is in the end of the Cygnus spur of the Milky Way and Andromeda just east of her mother, at least one of her arms outstretched to the aptly named Andromeda Galaxy. The three stars leading away from the galaxy make up one of Andromeda’s arms, the furthest being Mirach, followed by the bright star at the bottom edge, Almaak, making up her leg. Then moving back up and to the right in line with but going past Mirach is another bright star Delta Andromedae, right at the right edge of the photo, which makes up Andromeda’s left shoulder. Cassiopeia has five main stars in her constellation. Starting with Shedir, which means chest in Arabic is the bright star just above the small pink nebula NGC 281. Then moving left and up to Caph which is the bright star just left of a small blue gas or dust cloud, making up her head. Then again from Shedir, left and down into the bright blue glow of the star Navi, then back to the right and down, almost directly under Shedir is Ruchbah, which again in Arabic means knee. Finally moving down and to the left we find Cassiopeia’s foot at the star Segin which is near the bottom edge surrounded by blue colored gas or dust. Cassiopeia faces her daughter Andromeda.

Specific Feedback

My main questions are:

  1. Did I over cook the Cygnus spur, color wise? These were the colors present after doing a color calibration in Siril using Omega Cassiopeiae as the target star from the Simbad catalog to do a photometric color calibration after Siril did a plate solve for the stars in my image. Did I go over board on the colors?

  2. Does the rest of the sky look natural? I forgot to take Bias files while out in the field at temperature with my D850, so I processed the images without the bias files.

Any other comments most welcome.

Technical Details

Nikon D5850
Nikon 50mm f/1.8 MF lens
iOptron SkyGuider Pro for tracking
Photographed in the Sierra Nevada this past weekend after the storm cleared at an elevation of 4800 feet.
I took 13 images at 4 minute exposures, at ISO 1600 at an aperture of f4, for a total of 52 minutesof integration.
I stacked and registered the exposures in Siril using the following workflow: Auto stacking and registration, Background Extraction, Color Calibration using Photometric color calibration, Removed Green Noise, Removed stars using Starnet++, Adjusted color saturation.
Then I opened the starless image in PS and performed a number of edits to get the colors to my liking.
Then back to Siril for Star Recomposition using the edited starless image and the star mask generated by Starnet++

Critique Template

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  • Vision and Purpose:
  • Conceptual:
  • Emotional Impact and Mood:
  • Composition:
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  • Depth and Dimension:
  • Color:
  • Lighting:
  • Processing:
  • Technical:
2

This is a very cool image and am amazed at the detail you were able to capture at 50mm. I’m not sure what the colors should be, but I like the results of your post processing. The composition is perfect for one’s imagination. I like this one as presented…Jim

3

I am in awe of the technical mastery to create such an image, and even more your appreciation and story-telling of the Greek and Arabic interpretations of the stars. I was not able to understand your story in terms of the image, but I am not very good at “connecting the dots”. I wonder what the image would be if a large percentage of the smaller lights were not present.

4

Totally incredible for a “regular camera and lens” capture! The galaxy is wonderful!! I’m a little uncertain about the nebulosity colors – they look a little overdone. But you got fantastic results with under an hour of integration.

The tracker is working very well – how are you mounting the camera/lens?

I need to try more of this “wide-angle” imaging!

You say you forgot to take Bias files, but do you mean Darks? Biases are not temp-dependent.

5

Thanks @Diane_Miller. No, I took darks out there after taking the lights at the same temperature and shutter time. I thought bias files had to be at the same temperature as the lights only at the fastest shutter speed possible. If not then I can take them here and reprocess.

I was a little unhappy with the nebulosity colors. I have seen the blue and cyan colors before in that part of the Cygnus spur, but the green and red were there in the file. I tried to reduce them but had a hard time doing so, thinking that my lack of bias frames might have been the culprit.

6

Biases are for correcting fixed-pattern noise in the sensor, and are independent of temp and taken in the dark at the fastest SS. Here’s a good article. And regarding Darks, I’m a little fanatical about not only putting on the lens cap but hanging a several-layer thick velvet cloth over the front of the lens. The lens caps on my daytime lenses leak like crazy – easy to test.